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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // 1.isNaN: Not a Number
        var name = "Jack";
        console.log(isNaN(name));
        var age = 20;
        console.log(isNaN(age));
        // 2.parseInt:return integer
        var x = "5";
        console.log(typeof(parseInt(x)));
        // 3.parseFloat: return floating point number
        var y = "5.35";
        console.log(parseFloat(y));
        console.log(typeof(parseFloat(y)));
        // 4.eval() :evaluate
        var a = 1;
        var b = 3;
        console.log(eval(a + b));
        // 5.prompt():允许用户输入
        var inputName = prompt("Enter Your Name:", "");
        console.log(inputName);
        // 6.confirm(): 确认，校验或接受任务
        var res = confirm("确定退出系统？");
        console.log(res);
        // 7.alert():弹出框
        alert("hello");
    </script>
</body>

</html>